This invention relates to an image reading apparatus that reads image information from a read object.
Conventional image reading apparatus are known to be of a flatbed type or of an ADF (Auto Document Feeder) type. A flatbed type image reading apparatus conveys a reading unit under a read object (document) in static condition, thereby to make the reading unit read image information of the read object. An ADF type image reading apparatus conveys a read object (document) over a reading unit in fixed condition, thereby to make the reading unit read image information of the read object.
Known driving sources for conveying the reading unit and the read object are a pulse motor and a DC motor. A pulse motor is widely used because of simplicity of position control and convenience in constitution of a control system. However, a pulse motor produces large noise and consumes more power than a DC motor while driven. Furthermore, a pulse motor is inferior to a DC motor in velocity of scanning. Therefore, for the purpose of reducing noise and power consumption while driven, as well as improving velocity performance, an image reading apparatus adopting a DC motor as a driving source is actively developed in recent years.